The Endocrine system!
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Transcript of The Endocrine system!
The Endocrine System!
• A system of glands throughout the body that regulates and disperses hormones within the body.
• The word endocrine derives from the Greek words "endo" meaning inside, within, and "crinis" for secrete.
• The endocrine system is a collection of glands that secrete chemical messages we call hormones. These signals are passed through the blood to arrive at a target organ, which has cells possessing the appropriate receptor.
• Exocrine glands (not part of the endocrine system) secrete products
that are passed outside the body. Sweat glands, salivary glands, and digestive glands are examples of exocrine glands.
What is a hormone?
• A hormone is a chemical that the endocrine glands send throughout your body.
Hormones (which can be protein or lipid in nature) affect your growth, puberty, metabolism, weight, figure, shape, physical appearance, reproductive behavior, and emotions.
Hormones regulate almost everything in your body (growth, weight, digestion, ability to reproduce, stress response, how tired you are, etc)
How do hormones work?• Endocrine glands secrete potent hormones into
the bloodstream that affect target cells with specific receptors and have no effect on other cells
• Chemically, hormones are divided into steroids, amines, peptides, proteins, and glycoproteins
• Ex's--estrogen, testosterone, cortisol• In cholesterol form• Enter target cell and bind to
receptors--this forms complexes in the nucleus
• complexes activate specific genes so certain proteins are synthesized
Steroid Hormones
1. Steroids are soluble in lipids, allowing them to diffuse through the cell membrane
2. The steroid hormone combines with the according protein receptor, enters nucleus
3. The hormone-receptor complex activates transcription of specific genes into mRNA molecules
4.mRNA leave nucleus, enter cytoplasm, and associate with ribosomes to direct synthesis of specific proteins
5. Newly synthesized proteins carry out specific effects associated w/steroid hormone in question
Non-steroid Hormones• Bind to receptors in
target cell membrane, signals G protein, which activates 2ndary messenger molecules, which in turn activate protein kinases
Negative FeedbackMost hormones are regulated under a
negative feedback system
• The hypothalamus of a human responds to temperature fluctuations and responds accordingly. If the temperature drops, the body shivers to bring up the temperature and if it is too warm, the body will sweat to cool down due to evaporation. http://examples.yourdictionary.com/examples/examples-of-negative-feedback.html
Hypothalamus• A small very important gland, about the size of a
pearl• Alters behavioral and autonomic functions
The main link between the nervous and the endocrine system
• Contains three main regions; Anterior, Tuberal, and Posterior each containing their own nuclei
with their own functions. ex: the lateral nuclei of the anterior region of the hypothalamus regulates thirst and hunger.
• Both neurotransmitters AND hormones can be found within the hypothalamus
• Neurotransmitters are mostly synthesized within the hypothalamus
PrimarilyAch
GABAGlutamateSerotoninDopamine
Norepinephrine
• The "control" center for the pituitary gland
• Sends out Tropic hormones to tell the pituitary to secrete hormones
Steps from Hypothalamus to Pituitary:
the hypothalamus secretes tropic hormones that affect the anterior pituitary and these hormones enter the blood
the blood vessels running away from the hypothalamus run directly into the anterior pituitary from the hypothalamus, before continuing their journey through the body
the anterior pituitary gets direct exposure to the blood from the hypothalamus; this blood is chock full o' hypothalamic hormones
the hypothalamic hormones reach the cells of the anterior pituitary and exert their effect
the anterior pituitary secretes its hormones
Hormones secreted by the hypothalamus
Anti-diuretic hormone (ADH)
Corticotropin-releasing hormone (CRH)
Gonadotropin-releasing hormone (GnRH)
Growth hormone-releasing hormone (GHRH) or growth hormone-inhibiting hormone
(GHIH)Oxytocin: Prolactin-releasing hormone (PRH) or prolactin-inhibiting
hormone (PIH)
("Hypothalamus and Pituitary." STCC Faculty Webpages. N.p., n.d. Web. 8 May 2013. <http://faculty.stcc.edu/AandP/AP/AP2pages/U)
Hypothalamic DiseaseCan cause
hypothalamic disease:
Anorexia
Bleeding
Bulimia
Genetic disorders
Growths (tumors)
Head trauma
Infections and swelling (inflammation)
Malnutrition
Radiation
Surgery
Too much iron
Symptoms depend on the complication:Pituitary: Growth defectsLate puberty
Hypthyroidism:Cold intoleranceConstipationDepressed moodFatigueHair or skin changesHoarsenessImpotenceLoss of body hair and muscle (in men)Mental slowingMenstrual cycle changesWeight gain
Tumor:HeadachesLoss of vison
Adrenal:DizzinessWeakness
Blood and Urine tests can check balances in hormones
Also MRI or CAT scans can detect changes in levels
Treatment:Radiation (tumors)Hormonal replacement
PITUITARY GLAND• Hypothalamus controls most pituitary gland
secretions• Pituitary gland has anterior and posterior lobe
Anterior Pituitary Hormones• Growth hormone (GH): stimulates cells to
enlarge and divide more frequently (cell regeneration)
• Prolactin (PRL): stimulates a woman's milk production
• Thyroid-stimulating hormone (TSH): controls hormone secretion from the thyroid gland
• Adrenocorticotropic hormone (ACTH): controls hormone secretion from adrenal cortex
• Also regulates gonadotropins: follicle-stimulating hormone (FSH) and luteinizing hormone (LH)
Posterior Pituitary• Posterior lobe contains many
neuroglial cells and nerve fibers
• Antidiuretic hormone (ADH) : reduces volume of water kidneys excrete
• Oxytocin (OT): contracts muscles in uterine wall, contracts cells associated with producing/ejecting milk
PITUITARY GLAND DISORDERS
Pituitary adenoma : benign tumor
Hypopituitarism: decreased secretion of one or more hormones in pituitary gland, rare
Acromegaly: AP releases GH after epiphyseal plates close, commonly
involves GH-producing tumor
PINEAL GLAND• small structure attached to
thalamus• secretes MELATONIN in response
to light conditions outside of the body
MELATONIN• Aids circadian rhythms--
patterns of activity associated with night and day cycles
• Changing melatonin levels throughout day influence body's sense of time--sleep-wake rhythm, fertility cycles
• Inhibits secretion of of gonadotropins from AP, so may influence female reproductive cycle/puberty
Thyroid
• The Thyroid is "butterfly-shaped"• produces thyroxine -prohormone
and smaller amounts of triiodothyronine -active hormone
• The thyroid gland is a component of the hypothalamic-pituitary-thyroid axis- negative feedback control system.
Parathyroid
• located in the neck behind the thyroid
• hormones regulate the use and function of calcium and phosphorus
Ovaries & Testes
These are the two main glands in the reproductive system.
(Ovaries are female, Testes are male)
The OvariesThe ovaries have two main reproductive functions in
the body. They produce oocytes (eggs) for fertilization and they produce the reproductive hormones, estrogen and progesterone.
They produce progesterone and estrogen, which are themain hormones vital to themenstrual cycle
Menstrual Cycle• Gonadotropin-releasing hormone (GnRH)• Follicle-stimulating hormone (FSH)• Luteinizing hormone (LH)• Estrogen• Progesterone• TestosteroneDuring the menstrual cycle, GnRH is released first by the
hypothalamus. This causes a chemical reaction in the pituitary gland and stimulates the production of FSH and LH. Estrogen, progesterone, and testosterone are produced by the ovaries in reaction to stimulation by FSH and LH. When these hormones work together, normal menstrual cycles occur.
TestesThe main hormone secreted by the testes is
testosterone, an androgenic (male) hormone. Testosterone is secreted by cells that
lie between the seminiferous tubules, known as the Leydig cells.
Disorders within the Testes and OvariesThe most common disorder in ovaries is
infertility. Ovarian cysts and cancer also occur.
Male infertility is also very common.Testicular cancer can also occur.
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